1. MODELING THE EFFECT OF PREFERENTIAL HERBIVORY IN TROPICAL FORESTS 2014 PEI Summer Internship Emily Shuldiner

2. Suchana Costa (‘14) Thesis: “Herbivory Constaints on Symbiotic N 2 -fixers in Young Recovering Tropical Rainforest” From “Herbivory Constraints on Symbiotic N2- fixers in Young Recovering Tropical Rainforest,” by Suchana Costa, 2014 Agua Salud: Mosaic. Retrieved from the Smithsonian Tropical Research Institute website, www.ctfs.si.edu/aguasalud/page/catchments/#forest

3. The big question: How does the observed herbivory pattern affect the tropical carbon sink? (A) Model the effect of the herbivory pattern identified by Costa at current CO 2 levels. (B) Model the effect the herbivory pattern, assuming rising CO 2 levels.

4. Medvigy et al. (2009), JGR Biogeosciences Modeling the N deficit: Ecosystem Demography model 2 (ED2) What goes in: Meteorology, Deposition What comes out: Number density of trees -- of a given size -- of a given plant functional type The cast: The newcomer: N-fixer The original trio of ED2 tropical trees (all non-fixers) (disturbed)

5. Incorporating Herbivory into the Model -From Suchana Costa’s 2014 senior thesis: -Nonfixers (PFT 2,3,4): 0.9% leaf removed / month -Fixers (PFT 30): 3.0% leaf removed / month -Herbivory represented in model as increase in underlying yearly leaf turnover rate.

6. A: Effect of Herbivory Two Possibilities: (1) Disproportionate fixer herbivory  Diminished fixer growth  Fixers less able to compete with non- fixers  Competitive advantage to non-fixers (2) Disproportionate fixer herbivory  Diminished fixer growth  Less available N in ecosystem  Non-fixers face severe N limitation  Competitive advantage to fixers

7. Hurting fixers hurts non-fixers

8. The importance of fixers

9. B: Effect of Elevated [CO 2 ] on Effect of Herbivory (1) How does increased [CO 2 ] affect fixer abundance? (2) How does increased [CO 2 ] affect the relative impact of herbivory.

10. Rising [CO 2 ] 0 increases net AGB

11. Forest Composition Solid line- No Herbivory Dotted line- Herbivory

12. % AGB Lost to Herbivory